Analysis of genetic abnormalities provides insights into genetic evolution of hyperdiploid myeloma

The genomic landscape of Vk*MYC myeloma highlights shared pathways of transformation between mice and humans

Multiple myeloma (MM) is a heterogeneous disease characterized by frequent MYC translocations. Sporadic MYC activation in the germinal center of genetically engineered Vk*MYC mice is sufficient to induce plasma cell tumors in which a variety of secondary mutations are spontaneously acquired and selected over time. Analysis of 119 Vk*MYC myeloma reveals recurrent copy number alterations, structural variations, chromothripsis, driver mutations, apolipoprotein B mRNA-editing enzyme, catalytic polypeptide (APOBEC) mutational activity, and a progressive decrease in immunoglobulin transcription that inversely correlates with proliferation. Moreover, we identify frequent insertional mutagenesis by endogenous retro-elements as a murine specific mechanism to activate NF-kB and IL6 signaling pathways shared with human MM. Despite the increased genomic complexity associated with progression, advanced tumors remain dependent on MYC. In summary, here we credential the Vk*MYC mouse as a unique resource to explore MM genomic evolution and describe a fully annotated collection of diverse and immortalized murine MM tumors.

The Vk*MYC Mouse Model recapitulates human multiple myeloma evolution and genomic diversity

Despite advancements in profiling multiple myeloma (MM) and its precursor conditions, there is limited information on mechanisms underlying disease progression. Clincal efforts designed to deconvolute such mechanisms are challenged by the long lead time between monoclonal gammopathy and its transformation to MM. MM mouse models represent an opportunity to overcome this temporal limitation. Here, we profile the genomic landscape of 118 genetically engineered Vk*MYC MM and reveal that it recapitulates the genomic heterogenenity and life history of human MM. We observed recurrent copy number alterations, structural variations, chromothripsis, driver mutations, APOBEC mutational activity, and a progressive decrease in immunoglobulin transcription that inversely correlates with proliferation. Moreover, we identified frequent insertional mutagenesis by endogenous retro-elements as a murine specific mechanism to activate NF-kB and IL6 signaling pathways shared with human MM. Despite the increased genomic complexity associated with progression, advanced tumors remain dependent on MYC expression, that drives the progression of monoclonal gammopathy to MM.

Increasing genomic discovery in newly diagnosed multiple myeloma: defining disease biology and its correlation to risk

Our understanding of MM genomics has expanded rapidly in the past 5-10 years as a consequence of cytogenetic analyses obtained in routine clinical practice as well as the ability to perform whole-exome/genome sequencing and gene expression profiling on large patient data sets. This knowledge has offered new insights into disease biology and is increasingly defining high-risk genomic patterns. In this manuscript, we present a thorough review of our current knowledge of MM genomics. The epidemiology and biology of chromosomal abnormalities including both copy number abnormalities and chromosomal translocation are described in full with a focus on those most clinically impactful such as 1q amplification and del(17p) as well as certain chromosome 14 translocations. A review of our ever-expanding knowledge of genetic mutations derived from recent whole-genome/exome data sets is then reviewed including those that drive disease pathogenesis from precursor states as well as those that may impact clinical outcomes. We then transition and attempt to elucidate how both chromosomal abnormalities and gene mutations are evolving our understanding of disease risk. We conclude by offering our perspectives moving forward as to how we might apply whole-genome/exome-level data in addition to routine cytogenetic analyses to improve patient outcomes as well as further knowledge gaps that must be addressed.

Multiple Myeloma: Molecular Pathogenesis and Disease Evolution

BACKGROUND

Multiple myeloma is the second most common hematologic malignancy, which to date remains incurable despite advances in treatment strategies including the use of novel substances such as proteasome inhibitors, immunomodulatory drugs, and monoclonal antibodies.

SUMMARY

The bone marrow-based disease is preceded by the 2 sequential premalignant conditions: monoclonal gammo-pathy of undetermined significance and smoldering myeloma. Plasma cell leukemia and extramedullary disease occur, when malignant clones lose their dependency on the bone marrow. Key genetic features of these plasma cell dyscrasias include chromosomal aberrations such as translocations and hyperdiploidy, which occur during error-prone physiologic processes in B-cell development. Next-generation sequencing studies have identified mutations in major oncogenic pathways and tumor suppressors, which contribute to the pathogenesis of multiple myeloma and have revealed insights into the clonal evolution of the disease, particularly along different lines of therapy. More recently, the importance of epigenetic alterations and the role of the bone marrow microenvironment, including immune and osteogenic cells, have become evident. Key Messages: We herein review the current knowledge of the pathogenesis of multiple myeloma, which is crucial for the development of novel targeted therapeutic strategies. These can contribute to the endeavor to make multiple myeloma a curable disease.

Genetic Abnormalities in Multiple Myeloma: Prognostic and Therapeutic Implications

Some genetic abnormalities of multiple myeloma (MM) detected more than two decades ago remain major prognostic factors. In recent years, the introduction of cutting-edge genomic methodologies has enabled the extensive deciphering of genomic events in MM. Although none of the alterations newly discovered have significantly improved the stratification of the outcome of patients with MM, some of them, point mutations in particular, are promising targets for the development of personalized medicine. This review summarizes the main genetic abnormalities described in MM together with their prognostic impact, and the therapeutic approaches potentially aimed at abrogating the undesirable pathogenic effect of each alteration.

AL amyloidosis: The effect of fluorescent in situ hybridization abnormalities on organ involvement and survival

Background

Systemic light chain (AL) amyloidosis is a clonal plasma‐cell neoplasm that carries a poor prognosis. Although AL amyloidosis and Multiple Myeloma (MM) can co‐exist and share various cytogenetic chromosomal abnormalities, little is known about Fluorescent in situ hybridization (FISH) and its prognostic relevance in AL amyloidosis.

Aim:

The study aims to evaluate the most prevalent FISH cytogenetic abnormalities in AL patients as independent prognostic factors, and assess the impact of cytogenetics on the survival of high‐risk cardiac AL patients.

Materials & Methods

This retrospective study reviewed 113 consecutive AL patients treated at The Ohio State University (OSU). Patients were divided into subgroups based on FISH data obtained within 90 days of diagnosis. Hyperdiploidy was defined as trisomies of at least 2 chromosomal loci. Primary endpoints were progression free survival (PFS) and overall survival (OS). Kaplan Meier curves were used to calculate PFS and OS. The log‐rank test and Cox proportional hazard models were used to test the equality of survival functions and further evaluate the differences between groups.

Results

FISH abnormalities were detected in 76% of patients. Patients with abnormal FISH trended toward lower overall survival (OS) (p=0.06) and progression free survival (PFS) (p=0.06). The two most prevalent aberrations were translocation t(11;14) (39%) and hyperdiploidy‐overall (38%). Hyperdiploidy‐overall was associated with worsening PFS (p=0.018) and OS (p=0.03), confirmed in multivariable analysis. Patients with del 13q most frequently had cardiac involvement (p=0.006) and was associated with increased bone marrow plasmacytosis (p=0.02). Cardiac AL patients with no FISH abnormalities had much improved OS (p=0.012) and PFS (p=0.018)

Conclusions

Our findings ultimately reveal the association of hyperdiploidy on survival in AL amyloidosis patients, including the high‐risk cardiac AL population.

Conventional Cytogenetics and Interphase Fluorescence In Situ Hybridization Results in Multiple Myeloma: A Turkey Laboratory Analysis of 381 Cases

Multiple myeloma (MM) is an uncontrolled proliferation of plasma cells and these cells play an important role in the immune system. In this research, we retrospectively analyzed cytogenetic abnormalities in 381 patients with MM. Conventional cytogenetic analysis was successful in 354 patients (92.9%). Chromosomal abnormalities were detected in 31.9% (113/354) and 45.8% (116/253) of patients screened with conventional cytogenetics and FISH, respectively. Of 113 patients with chromosomal abnormalities, 31 patients (27.4%) had hyperdiploid and 26 of 31 patients with hyperdiploidy had both numerical and structural anomalies. On the other hand, non-hyperdiploidy was observed in 62 patients (54.8%). The most common gains of chromosomes were 15, 9, 19 followed by 3, 5, 11, and 21. Whole chromosome losses were also frequent involving Y, 13 and 22 chromosomes. In our patients, 1q gain was determined in a total of 25 patients (22%), including 7 structural abnormalities and 19 unbalanced translocations causing complete or partial duplication of the long arm of chromosome 1. Although the breakpoints were different, t(1;5) balanced translocation and unbalanced translocations of t(1;2), t(1;3), t(1;7), t(1;16) and t(1;19) were observed twice. The most common structural abnormality was the deletion of the short arm of chromosome 13 (13q) or monosomy of chromosome 13 (-13) (24.1%, 61/253) in patients evaluated by FISH. Deletion involving chromosome 17p (del 17p) or monosomy of chromosome 17 (-17) were found in 31 (12.3%) patients. Translocations involving IgH regions were as follows: t(11;14)(q13;q32.33) in 22 (8.7%), t(4;14)(p16.3;q32.33) in 22 (8.7%) and t(14;16)(q32.33;q23.1) in 2 (0.8%) patients. In addition, t(14;17)(q32;q21) translocation was detected in a multiple myeloma patient for the first time in this study. There are a limited number of large study groups including both cytogenetic and FISH findings in MM patients. As the number of these studies increases, it is thought that new cytogenetic data can be guiding especially in clinical risk determination.

An adaptive trial design to optimize dose-schedule regimes with delayed outcomes

This paper proposes a two-stage phase I-II clinical trial design to optimize dose-schedule regimes of an experimental agent within ordered disease subgroups in terms of the toxicity-efficacy trade-off. The design is motivated by settings where prior biological information indicates it is certain that efficacy will improve with ordinal subgroup level. We formulate a flexible Bayesian hierarchical model to account for associations among subgroups and regimes, and to characterize ordered subgroup effects. Sequentially adaptive decision-making is complicated by the problem, arising from the motivating application, that efficacy is scored on day 90 and toxicity is evaluated within 30 days from the start of therapy, while the patient accrual rate is fast relative to these outcome evaluation intervals. To deal with this in a practical manner, we take a likelihood-based approach that treats unobserved toxicity and efficacy outcomes as missing values, and use elicited utilities that quantify the efficacy-toxicity trade-off as a decision criterion. Adaptive randomization is used to assign patients to regimes while accounting for subgroups, with randomization probabilities depending on the posterior predictive distributions of utilities. A simulation study is presented to evaluate the design's performance under a variety of scenarios, and to assess its sensitivity to the amount of missing data, the prior, and model misspecification.

Prognostic impact of hyperdiploidy in multiple myeloma patients with high-risk cytogenetics: a pilot study in China

PURPOSE

Multiple myeloma is genetically heterogeneous with varied clinical outcomes, primarily due to the coexistence of diverse numerical and structural cytogenetic abnormalities. The prognostic impact of hyperdiploidy in myeloma patients with high-risk cytogenetics remains controversial in Western studies and is unknown in China.

METHODS

We examined the cytogenetic features of hyperdiploidy in 201 Chinese patients with newly diagnosed myeloma using magnetic-activated cell sorting and interphase fluorescence in situ hybridization and analyzed the effect of hyperdiploidy on the prognosis of patients with high-risk cytogenetics.

RESULTS

Hyperdiploidy was detected in 50.7% (102/201) of the examined patients, and the incidence of hyperdiploidy coexisting with high-risk cytogenetics [del(17p13), +1q21 and adverse t(14q32)] was 33.8% (68/201). Survival analysis showed that the median progression-free survival (PFS) and 2-year overall survival (OS) of patients were better for hyperdiploidy than those for non-hyperdiploidy (43 vs. 20 months, P = 0.01; 86.8% vs. 70.5%, P = 0.04) and for standard-risk cytogenetics than those for high-risk cytogenetics (not reached vs. 23 months, P = 0.0001; 87.6% vs. 74.4%, P = 0.01). Strikingly, the high-risk cytogenetics patients with hyperdiploidy showed a better median PFS than those without hyperdiploidy (34 vs. 15 months, P = 0.01); however, compared to standard-risk cytogenetics patients, the median PFS and 2-year OS were poorer (34 months vs. not reached, P = 0.02; 78.8% vs. 87.6%, P = 0.05). The independent predictors of PFS were non-hyperdiploidy, high-risk cytogenetics, and bone marrow plasma cells ≥ 30%, with hazard ratios of 2.01 (95% CI 1.25-3.25), 2.56 (95% CI 1.38-4.74), and 1.81 (95% CI 1.08-3.05), respectively, and those for OS were non-hyperdiploidy and serum lactate dehydrogenase ≥ 250 U/L, with hazard ratios of 2.53 (95% CI 1.24-5.46) and 3.53 (95% CI 1.50-6.96), respectively.

CONCLUSIONS

These results suggest that the coexistence of hyperdiploidy may ameliorate the adverse prognosis of multiple myeloma patients with high-risk cytogenetics. High-risk cytogenetics patients without hyperdiploidy showed the worst prognosis.

Blind men and an elephant

In this issue of Blood, Pawlyn et al examine the prognostic implications of overlapping chromosomal abnormalities in multiple myeloma (MM), demonstrating that coexistence of hyperdiploidy does not mitigate the impact of high-risk abnormalities.

Coexistent hyperdiploidy does not abrogate poor prognosis in myeloma with adverse cytogenetics and may precede IGH translocations

The acquisition of the cytogenetic abnormalities hyperdiploidy or translocations into the immunoglobulin gene loci are considered as initiating events in the pathogenesis of myeloma and were often assumed to be mutually exclusive. These lesions have clinical significance; hyperdiploidy or the presence of the t(11;14) translocation is associated with a favorable outcome, whereas t(4;14), t(14;16), and t(14;20) are unfavorable. Poor outcomes are magnified when lesions occur in association with other high-risk features, del17p and +1q. Some patients have coexistence of both good and poor prognostic lesions, and there has been no consensus on their risk status. To address this, we have investigated their clinical impact using cases in the Myeloma IX study (ISRCTN68454111) and shown that the coexistence of hyperdiploidy or t(11;14) does not abrogate the poor prognosis associated with adverse molecular lesions, including translocations. We have also used single-cell analysis to study cases with coexistent translocations and hyperdiploidy to determine how these lesions cosegregate within the clonal substructure, and we have demonstrated that hyperdiploidy may precede IGH translocation in a proportion of patients. These findings have important clinical and biological implications, as we conclude patients with coexistence of adverse lesions and hyperdiploidy should be considered high risk and treated accordingly.

An old drug with a new future: bendamustine in multiple myeloma

INTRODUCTION

Bendamustine is a unique bifunctional alkylating agent with promising activity in multiple myeloma (MM). It is currently licensed in Europe for use as frontline treatment with prednisolone for patients with MM who are unsuitable for transplantation and who are contraindicated for thalidomide and bortezomib therapy.

AREAS COVERED

Studies evaluating the safety and efficacy of bendamustine administered alone or in combination in both the upfront and relapse settings of MM patients, including those with renal insufficiency, were reviewed. The use of bendamustine as conditioning for autologous stem-cell transplantation and the possibility of stem-cell mobilization after bendamustine therapy are discussed.

EXPERT OPINION

Bendamustine seems to be efficacious either in monotherapy or in combination with other drugs in previously treated or untreated patients. This is due to its unique mechanism of action including its ability to activate apoptosis and inhibit mitotic checkpoints, making it potentially more effective than other alkylating agents. Moreover, it has an acceptable toxicity profile and is suitable for patients with renal impairment. Finally, this drug does not seem to compromise the possibility of achieving a stem-cell mobilization. Nonetheless, data from Phase III studies demonstrating its effectiveness in terms of overall survival are not yet available.

Dissecting karyotypic patterns in non-hyperdiploid multiple myeloma: an overview on the karyotypic evolution

BACKGROUND

Multiple myeloma (MM) is a plasma cell disorder characterized by the presence of specific genetic and cytogenetic aberrations that define unique subgroups with different outcomes. On the basis of the ploidy status, MM can be subdivided into hyperdiploid MM (H-MM) and non-hyperdiploid MM (NH-MM). NH-MM is an entity that encompasses hypodiploid, pseudodiploid, and near tetraploid MM and is associated with a higher number of immunoglobulin heavy-chain (IgH) translocations.

MATERIALS AND METHODS

We have systematically analyzed the structure of the karyotypic evolution in NH-MM and identified several genetic features of their complex karyotypic patterns.

RESULTS

On the basis of statistical models used in complex karyotypes, we were able to identify the temporal order in which the genetic aberrations occur in NH-MM. In this analysis, whole chromosome losses and IgH translocations were commonly seen, and -13/13q- and t14q32 were defined as early genetic events in the karyotypic evolution of NH-MM. Furthermore, chromosome 1 and 17 abnormalities were associated with a late karyotypic phase of evolution consistent with the recognized pattern of acquired events deemed to be associated with these type of genetic aberrations.

CONCLUSION

Accumulation of genetic aberrations in NH-MM above a threshold results in malignant transformation.

Genomic instability in multiple myeloma: mechanisms and therapeutic implications

INTRODUCTION

Clonal plasma cells in multiple myeloma (MM) are typified by their nearly universal aneuploidy and the presence of recurrent chromosomal aberrations reflecting their chromosomal instability. Multiple myeloma is also recognized to be heterogeneous with distinct molecular subgroups. Deep genome sequencing studies have recently revealed an even wider heterogeneity and genomic instability with the identification of a complex mutational landscape and a branching pattern of clonal evolution.

AREAS COVERED

Despite the lack of full understanding of the exact mechanisms driving the genomic instability in MM, recent observations have correlated these abnormalities with impairments in the DNA damage repair machinery as well as epigenetic changes. These mechanisms and the resulting therapeutic implications will be the subject of this review.

EXPERT OPINION

By providing growth advantage of the fittest clone and promoting the acquisition of drug resistance, genomic instability is unarguably beneficial to MM cells, however, it may also well be its Achilles heal by creating exploitable vulnerabilities. As such, targeting presumptive DNA repair defects and other oncogenic addictions represent a promising area of clinical investigation. In particular, by inducing gene or pathway dependencies not present in normal cells, genomic instability can generate targets of contextual synthetic lethality in MM cells.

Perspectives in the treatment of multiple myeloma

INTRODUCTION

The development of proteasome inhibitor (PI) and immunomodulatory drugs (IMiDs) and advances in supportive care have considerably changed the treatment paradigm of multiple myeloma (MM) and significantly improved survival. Nevertheless, almost all patients show disease relapse and develop drug resistance.

AREAS COVERED

We review the prognostic stratification and therapeutic strategy for newly diagnosed MM patients. Furthermore, mechanisms of drug resistance are discussed. Data regarding newer drugs, currently undergoing examination, such as PI (carfilzomib, ONX0912, MLN9708, and marizomib), IMiDs (pomalidomide), histone deacetylase inhibitors (vorinostat and panobinostat), kinase inhibitors (temsirolimus, everolimus, and tanespimycin), and immune-based therapies (elotuzumab, siltuximab, MOR03087, and MMBT062) are reported.

EXPERT OPINION

The use of three to four drug combination therapies including PI and IMiDs has significantly impacted on MM patient outcome. Moreover, new insights into MM biology from high-throughput technologies and availability of newer and more efficacious drugs will continue to influence our approach to MM treatment. In the immediate future molecular subgroup-specific trials using targeted agents may represent a very important step toward evaluating impact of interfering with relevant signaling pathways in MM. With the continued rapid evolution of progress in this field, MM will become a chronic illness having sustained complete response in a significant number of patients.

Classify hyperdiploidy status of multiple myeloma patients using gene expression profiles

Multiple myeloma (MM) is a cancer of antibody-making plasma cells. It frequently harbors alterations in DNA and chromosome copy numbers, and can be divided into two major subtypes, hyperdiploid (HMM) and non-hyperdiploid multiple myeloma (NHMM). The two subtypes have different survival prognosis, possibly due to different but converging paths to oncogenesis. Existing methods for identifying the two subtypes are fluorescence in situ hybridization (FISH) and copy number microarrays, with increased cost and sample requirements. We hypothesize that chromosome alterations have their imprint in gene expression through dosage effect. Using five MM expression datasets that have HMM status measured by FISH and copy number microarrays, we have developed and validated a K-nearest-neighbor method to classify MM into HMM and NHMM based on gene expression profiles. Classification accuracy for test datasets ranges from 0.83 to 0.88. This classification will enable researchers to study differences and commonalities of the two MM subtypes in disease biology and prognosis using expression datasets without need for additional subtype measurements. Our study also supports the advantages of using cancer specific characteristics in feature design and pooling multiple rounds of classification results to improve accuracy. We provide R source code and processed datasets at www.ChengLiLab.org/software.

Emerging biological insights and novel treatment strategies in multiple myeloma

INTRODUCTION

Survival in multiple myeloma (MM) has improved significantly in the past 10 years due to new treatments, such as thalidomide and lenalidomide (immunomodulatory drugs or IMiDs) bortezomib and advances in supportive care. Nevertheless, almost all MM patients show disease relapse and develop drug resistance.

AREAS COVERED

The authors review the therapeutic approach for untreated MM patients. Furthermore, the prognostic stratification of patients and the proposed risk-adapted strategy are discussed. Finally, preclinical and clinical data regarding newer antimyeloma agents, currently undergoing examination such as proteasome inhibitors (PIs, carfilzomib), IMiDs (pomalidomide), epigenetic agents (histone deacetylase inhibitors vorinostat and panobinostat), humanized monoclonal antibodies (elotuzumab and MOR03087) and targeted therapies (inhibitors of NF-κB, MAPK, HSP90 and AKT) are reported.

EXPERT OPINION

MM patient outcome has remarkably improved due to the use of three to four drug combination therapies including PIs and IMiDs, which target the tumor in its bone marrow microenvironment, however MM treatment remains challenging. The use of high-throughput techniques has allowed to discover new insights into MM biology. The identification of candidate therapeutic targets and availability of respective investigative agents will allow for a substantial progress in the development and implementation of personalized medicine in MM.

Latest advances and current challenges in the treatment of multiple myeloma

Effectively treating patients with multiple myeloma is challenging. The development of therapeutic regimens over the past decade that incorporate the proteasome inhibitor bortezomib and the immunomodulatory drugs thalidomide and lenalidomide has been the cornerstone of improving the outcome of patients with myeloma. Although these treatment regimens have improved patient survival, nearly all patients eventually relapse. Our improved understanding of the biology of the disease and the importance of the microenvironment has translated into ongoing work to help overcome the challenge of relapse. Several classes of agents including next-generation proteasome inhibitors, immunomodulatory agents, selective histone-deacetylase inhibitors, antibody and antitumor immunotherapy approaches are currently undergoing preclinical and clinical evaluation. This Review provides an update on the latest advances in the treatment of multiple myeloma. In particular, we focus on novel therapies including modulating protein homeostasis, kinases inhibitors, targeting accessory cells and cytokines, and immunomodulatory agents. A discussion of the challenges associated with these therapeutic approaches is also presented.

Trisomies in multiple myeloma: impact on survival in patients with high-risk cytogenetics

Routine incorporation of FISH into multiple myeloma (MM) diagnostic testing has led to a better appreciation of the heterogeneity of genetic abnormalities associated with this disease. We studied a group of 484 patients with newly diagnosed symptomatic MM to better understand the prevalence of the various abnormalities and the prognostic significance of the overlapping abnormalities. A translocation involving the IgH locus and 1 of the 5 recurrent partner chromosomes was seen in 161 (33%) patients, and 275 (57%) had trisomy of at least 1 odd-numbered chromosome. High-risk FISH, defined as the presence of t(4;14), t(14;16), t(14;20), or loss of P53, was seen in 115 (24%) patients; the median overall survival for this group was 3.9 years, compared with "not reached" for standard-risk patients (P < .001). Among the patients with high-risk FISH, 49 patients who also had at least 1 trisomy had a median overall survival that was not reached, compared with 3 years for high-risk patients without a concurrent trisomy (P = .01). Based on the current findings, we conclude that the presence of trisomies in patients with t(4;14), t(14;16), t(14;20), or p53 deletion abnormalities in MM ameliorates the usual adverse impact associated with these prognostic markers.

Chromosome abnormalities defined by conventional cytogenetics in plasma cell leukemia: what have we learned about its biology?

Cancer cells are characterized by having chromosomal abnormalities. The number of aberrations and the specific chromosomes affected are likely correlated with tumor progression. In this study, we analyzed the karyotype of 126 plasma cell leukemia (PCL) patients to identify the most frequently occurring imbalances and to design a model of karyotypic evolution. The Mitelman database of chromosome was searched and abnormal karyotypes were assessed. The main clones were analyzed and chromosomal gains and losses were used to design a model of genetic acquisition based on the calculation of a variable called time to occurrence. Our comprehensive study of genetic abnormalities of a large number of PCL karyotypes suggests that PCL is mainly characterized by the presence of whole chromosome losses as well as IgH rearrangements which is similar to that observed in non-hyperdiploid multiple myeloma (MM). Temporal analysis suggests that most PCL have around 10 abnormalities at diagnosis. It is possible that accumulation of abnormalities such as 17p13 (TP53) and 1p losses may trigger the extramedullary features of PCL. Our study demonstrates that cytogenetics is a valuable tool to evaluate the role of genetic imbalances on karyotypic evolution by using a mathematical model.

The prognostic significance of cytogenetics and molecular profiling in multiple myeloma

Multiple myeloma (MM) is a plasma cell malignancy characterized by very complex cytogenetic and molecular genetic aberrations. In newly diagnosed symptomatic patients, the modal chromosome number is usually either hyperdiploid with multiple trisomies or hypodiploid with one of several types of immunoglobulin heavy chain (Ig) translocations. The chromosome ploidy status and Ig rearrangements are two genetic criteria that are used to help stratify patients into prognostic groups based on the findings of conventional cytogenetics and fluorescence in situ hybridization (FISH). In general, the hypodiploid group with t(4;14)(p16;q32) or t(14;16)(q32;q23) is considered a high-risk group, while the hyperdiploid patients with t(11;14)(q13;q32) are considered a better prognostic group. As the disease progresses, it becomes more proliferative and develops a number of secondary chromosome aberrations. These secondary aberrations commonly involve MYC rearrangements, del(13q), del(17p), and the deletion of 1p and/or amplification of 1q. Of the secondary aberrations, del(17p) is consistently associated with poor prognosis. All of these cytogenetic aberrations and many additional ones are now identified by means of high resolution molecular profiling. Gene expression profiling (GEP), array comparative genomic hybridization (aCGH), and single-nucleotide polymorphism (SNP) arrays have been able to identify novel genetic aberration patterns that have previously gone unrecognized. With the integration of data from these profiling techniques, new subclassifications of MM have been proposed which define distinct molecular genetic subgroups. In this review, the findings from conventional cytogenetics, interphase FISH, GEP, aCGH, and SNP profiles are described to provide the conceptual framework for defining the emerging molecular genetic subgroups with prognostic significance.

Hyperdiploidy is less frequent in AL amyloidosis compared with monoclonal gammopathy of undetermined significance and inversely associated with translocation t(11;14)

In multiple myeloma (MM) pathogenesis, hyperdiploidy and nonhyperdiploidy are recognized as 2 major cytogenetic pathways. Here, we assessed the role of hyperdiploidy in 426 patients with monoclonal plasma cell disorders, among them 246 patients with AL amyloidosis (AL), by interphase fluorescence in situ hybridization. Hyperdiploidy was defined by a well-established score requiring trisomies for at least 2 of the 3 chromosomes 5, 9, and 15. The hyperdiploidy frequency in AL was a mere 11% compared with 30% in monoclonal gammopathy of undetermined significance (P < .001) and 46% in AL with concomitant MM I (P < .001). Overall, hyperdiploidy was associated with an intact immunoglobulin, κ light chain restriction, higher age, and bone marrow plasmacytosis, but was unrelated to the organ involvement pattern in AL. Clustering of 6 major cytogenetic aberrations in AL by an oncogenetic tree model showed that hyperdiploidy and t(11;14) were almost mutually exclusive, whereas gain of 1q21 favored hyperdiploidy. Deletion 13q14 and secondary IgH translocations were equally distributed between ploidy groups. We conclude that the interphase fluorescence in situ hybridization–based hyperdiploidy score is also a feasible tool to delineate hyperdiploid patients in early-stage monoclonal gammopathies and that the cytogenetic pathogenetic concepts developed in MM are transferable to AL.

Relationship between elevated immunoglobulin free light chain and the presence of IgH translocations in multiple myeloma

Elevated immunoglobulin free light chain (FLC) level and abnormal FLC ratio are commonly seen in multiple myeloma (MM) and have prognostic implications. We hypothesized that presence of immunoglobin heavy chain (IgH) translocations leads to unbalanced production of light chains and more extreme abnormalities of FLC, and may explain the prognostic value of FLC. We studied 314 patients with newly diagnosed MM enrolled in a phase III trial, in whom results of fluorescence in situ hybridization testing and data on serum FLC levels were available. Cytogenetic analyses and FLC estimates were performed on stored samples and results were correlated with clinical data. The median ratio (FLC ratio) and the absolute difference (FLC diff) between the involved and uninvolved FLC were higher among those with IgH translocations, especially t(14;16). In multivariate analysis, the prognostic value of FLC estimates on progression-free and overall survival were independent of high-risk IgH translocations t(4;14) and t(14;16). A combination of the risk factors; either abnormal FLC estimate and/or the presence of high-risk IgH translocation, achieved better prognostic stratification. We conclude that patients with IgH translocations have higher FLC levels and abnormal ratios, but the prognostic effect of FLC is only partially explained by translocation status. A system including both these risk factors allows better prediction of outcome.

Recent advances in quantitative chimerism analysis

Quantitative chimerism analysis is a diagnostic tool used to monitor engraftment kinetics after allogeneic stem cell transplantation. It reflects the proportion of recipient and donor genotypes and is based on the identification of genetic markers characteristic to a given transplant pair. Currently, PCR amplification of short tandem repeats and single-nucleotide polymorphism-specific quantitative real-time PCR are the most widely used techniques for this purpose. In this review, we will address advances as well as technology-specific imperfections, of both techniques that have emerged over the recent years. We will discuss new principles that may simplify assay design, and improve its robustness and reliability. A better chimerism assay could then guide clinical interventions and may, eventually, improve the outcome of allogeneic stem cell transplantation.

High expression of BCL3 in human myeloma cells is associated with increased proliferation and inferior prognosis

BACKGROUND

BCL3 is a putative oncogene encoding for a protein belonging to the inhibitory kappaB-family. We experienced that this putative oncogene was a common target gene for growth-promoting cytokines in myeloma cell lines.

METHODS

Gene expression of BCL3 was studied in 351 newly diagnosed myeloma patients, 12 patients with smouldering myeloma, 44 patients with monoclonal gammopathy of undetermined significance and 22 healthy individuals. Smaller material of samples was included for mRNA detection by RT-PCR, protein detection by Western blot and immunohistochemistry, and for cytogenetic studies. A total of eight different myeloma cell lines were studied.

RESULTS

Bcl-3 was induced in myeloma cell lines by interleukin (IL)-6, IL-21, IL-15, tumor necrosis factor-alpha and IGF-1, and its upregulation was associated with increased proliferation of the cells. In a population of 351 patients, expression levels of BCL3 above 75th percentile were associated with shorter 5-yr survival. When this patient population was divided into subgroups based on molecular classification, BCL3 was significantly increased in a poor risk subgroup characterized by overexpression of cell cycle and proliferation related genes. Intracellular localization of Bcl-3 was dependent on type of stimulus given to the cell.

CONCLUSION

BCL3 is a common target gene for several growth-promoting cytokines in myeloma cells and high expression of BCL3 at the time of diagnosis is associated with poor prognosis of patients with multiple myeloma (MM). These data may indicate a potential oncogenic role for Bcl-3 in MM.

Secondary genomic rearrangements involving immunoglobulin or MYC loci show similar prevalences in hyperdiploid and nonhyperdiploid myeloma tumors

The pathogenesis of multiple myeloma (MM) is thought to involve at least two pathways, which generate hyperdiploid (HRD) or nonhyperdiploid (NHRD) tumors, respectively. Apart from chromosome content, the two pathways are distinguished by five primary immunoglobulin heavy chain (IGH) rearrangements (4p16, FGFR3, and MMSET; 6p21, CCND3; 11q13, CCND1; 16q23, MAF; 20q12, MAFB) that are present mainly in NHRD tumors. To determine the prevalence and structures of IGH, immunoglobulin (IG) light chain, and MYC genomic rearrangements in MM, we have done comprehensive metaphase fluorescent in situ hybridization analyses on 48 advanced MM tumors and 47 MM cell lines. As expected, the prevalence of the five primary IGH rearrangements was nearly 70% in NHRD tumors, but only 12% in HRD tumors. However, IGH rearrangements not involving one of the five primary partners, and IG light chain rearrangements, have a similar prevalence in HRD and NHRD tumors. In addition, MYC rearrangements, which are thought to be late progression events that sometimes do not involve an IG heavy or light chain locus, also have a similar prevalence in HRD and NHRD tumors. In contrast to the primary IGH rearrangements, which usually are simple balanced translocations, these other IG rearrangements usually have complex structures, as previously described for MYC rearrangements in MM. We conclude that IG light chain and MYC rearrangements, as well as secondary IGH rearrangements, make similar contributions to the progression of both HRD and NHRD MM tumors.

Treatment of newly diagnosed multiple myeloma based on Mayo Stratification of Myeloma and Risk-adapted Therapy (mSMART): consensus statement

Multiple myeloma is a neoplastic plasma cell dyscrasia that on a yearly basis affects nearly 17,000 individuals and kills more than 11,000. Although no cure exists, many effective treatments are available that prolong survival and improve the quality of life of patients with this disease. The purpose of this consensus is to offer a simplified, evidence-based algorithm of decision making for patients with newly diagnosed myeloma. In cases in which evidence is lacking, our team of 18 Mayo Clinic myeloma experts reached a consensus on what therapy could generally be recommended. The focal point of our strategy revolves around risk stratification. Although a multitude of risk factors have been identified throughout the years, including age, tumor burden, renal function, lactate dehydrogenase, beta2-microglobulin, and serum albumin, our group has now recognized and endorsed a genetic stratification and patient functional status for treatment.